All of these keep a pool of worker processes, they don't fork each request. With a non-trivial application the speed difference is negligible, though the memor

All of these keep a pool of worker processes, they don't fork each request. With a non-trivial application the speed difference is negligible, though the memory difference is not. PHP also has language-level isolation from request to request, but extensions are still long lived and require the process to be killed in some cases when they misbehave.